Machine for plastering walls



March 17, 1959 MACHINE FOR PLASTERING WALLS 3 Sheets-Sheet 1 Filed Sept. 15, 1953 bro-$5.

INVENTOR Geo/"ye Ocfa w'o oe fl/encar Cab/"a/ @6421 91044071 ATTORNEY G. 0. DE ALENCAR CABRAL MACHINE FOR PLASTERING WALLS March 17, 1959 3 SheetsSheet 2 Filed Sept. 15, 1953 INVENTOR llll ll I .I 6 I &1!

a vl'wl a Georye Ocfaw'o de A/encar' Cabral ATTORNEY Filed Sept. 15, 1953 March 17, 1959 e. 0. DE ALENCAR CABRAL 2,8

MACHINE FOR PLASTERING WALLS I s Sheets-Sheet a II E- 5 INVENTOR 6 George 0cm vl'o c/e A/encar Cabral ATTORNEY United States Patent y 2,877,641 1 MACHINE non PLASTERING WALLS George Octavio de Alencar Cabral, Rio de Janeiro, Brazil 7 Application September 15, 1953, Serial No. 380,319

Claims priority, application Brazil August 14, 1953 4 Claims. (Cl. 72-130) The present invention relates to the plastering of walls and pertains to an. improved machine designed for the application of plastering on walls and similar work. This type of work (plastering, coating and other operations) is nowadays usually performed manually, with the use of mortarboards, rulers, trowels and similar utensils. .Thejmachine of this invention will execute this type 2,877,641 Patented Mar. 17,

p to be portable, too big to pass through ordinary door of work in a better manner and in less time, besides consuming less material and labor. Using the conventional kind of mortar or some other similar plastering material, the machine of this invention will provide mechanization for .many operations now performed manually by masons A-few existing machines may be capable of rendering easier this masons job, both as regards rough and, final wall plastering. However, none of these last machines will execute the work in such a complete vand simultaneousmanner as the one herein described.

' Although many similar machines have been previosuly devised for the plastering or rough casting of walls and ceilings,-not one of them has as yet worked in a sufiiciently satisfactory manner to bring about its general use, so that the problem is as yet far from being solved.

, The problem to be solved by a machine of the type herein referred to is the rough casting or plastering of vertical plane surfaces reaching from about 20 cm. above floor-level to almost ceiling height, a total height of anywhere from 2.5 to 5 m. and, thus, the apparatus requires, as in most other similar devices, a vertical framework or trestle-like 7 structure horizontally movable in front of the wall to be plastered and a vertically and horizontally movable hopper or casing mounted on the trestlelike supporting structure. However, the novel and improved machine herein disclosed operates in an entirely different manner, thus ensuring better and more lasting results,

The novel wall plastering machine herein described is exemplified and illustrated in the hereunto attached drawings, wherein,

. Figure 1 is a perspective viewof a mortar-containing and applying casing forming a part of the invention.

. Figure 2 is a partially broken away perspective view of the, assembled machine.

. Figure 3 is a side view thereof.

Before starting to describe in detail the machine for plastering walls herein claimed, it should be pointed out that it comprises three principal parts; a base whereupon is mounted an electric motor and which also serves as a basefor the whole assembly; a trestle or column designed to receive guide rails for the mortar casing; and a casing designed to receive mortar and to applyand-compress the mortar over the surface of the wall.

,The base-may be easily separated from the remaining parts of the machine in order to make it easier to transport the machine from one room to another. Such ease of transportation is an essential condition for the practical use of-the machine, since a large and cumbersome machine would usually be useless-orimpractical.

In other words, a plastering machine too cumbersome openings or too heavy to be moved about, for example by two men, would constitute merely a theoretical solution of the problem, with no practical possibilities. The machine herein described meets this important condition.

Base 1 is a square wooden or steel structure resting on four casters 2, 2 which permit movement thereof in any direction along the floor of the room to be plastered. 'On base 1 is mounted an electric motor 3 capable of driving twin drums 4, 4, preferably by means of clutch means actuatable by the operator. The base 1 may be, however, maintained in a fixed operating position by means of two vertical threaded shafts 5, 5' which are provided with hand-wheels 6, 6' and may therefore be screwed on to a nut-like part attached to the base 1, in order to engage the floor level, thus raising the two rear casters 2', 2' so as to fix the base 1 in position.

From the end of base 1 opposite drums 4, 4' and motor 3 rises a trestle or column, comprising two substantially vertical front posts 7, 7' which are L-shapecl in cross sectional area and two slightly sloping rear posts, 8, 8' joined together'at convenient distances by means of cross-pieces 9 and struts 10.

The casing which forms one of the most important parts of the machine comprises the casing proper 11, the piston 12 and the two piston rods 13, 13' and their respective sleeves, which rest on a cross-head 33 (Fig. 1) at the back part of the casing, as Well as-some other accessory parts later to. be-described. The casing 11 may travel vertically along two rails 14, L-shaped in cross sectional area and the rails 7, 7 over which it slides by means of four T-shaped shoes 15. Within the casing 11 operates a piston 12 made of a rectangular metal strip afiixed to two rods 13, 13. The piston 12 slides without touching the casing 11 (preferably having an all around play of about 2 mm. and supported only by its rods) and pushes and compresses the plaster against the wall. To the front surface of the casing 11, two blades or laminations 16, 17 are. attached. The upper one 16 which is hereinafter nominated rough plastering blade or knife 16, is really an assembly of three flexible blades 16, 16, 16" the lower edges of which project approximately 3 cm. beyond the alignment of the leading or forward posts or rails 7, 7- (the alignment lying in the same plane as the plastering to be executed). This knife or blade 16 receives the 'mortar from the upper third of the casing 11 and compresses it against the wall, thereby executing the rough plastering operation. The flexible'blade follows the wall formation and provides initial compressive action nearer thereto. The second knife or final plastering blade 17 is attached to the front face of the casing 11, at the same level as'the lower edge thereof. It is a rigid metal sheet or blade, the lower edge of which lies in alignment with the front rails 7, 7'. This blade 17 receives the mortar coming from the two lower thirds of the casing 11 and compresses it against the rough plastering, thereby executing the final plastering. On both lateral surfaces of the casing and at the ends of an imaginary axis passing through the center of gravity of the former (mean center of gravity, as it executes displacements during operation), 'there are two pulleys 18, 18 over which pass chains 19, 19 leading from the ends of an arm 31 (Fig. 1) uniting said two piston rods 13, 13' and which reach up to the top part of the column, whence said chains 19, 19' go on to the two drums 4, 4' actuated by the motor 3 and installed on the machine base 1. Between these drums 4, 4' and the'motor 3 there is provided a reduction gear 20 selected so that the rising of the casing 11 may take about 30 seconds, since this is the speed which has proved most satisfactory in operation. At the upper part of the column 7, 7, 8, 8 said two hain .1 an 19' Pass o er wo pull ys keyed onto the ends 'of shafts which go from side to side of the column. Theseshafts are meant to equalize the stresses exerted by both chains 19, 19 on the easing 11, even though one of them should have a greater play in its connection with its drum. From these pulleys 21, 21 said chains 19, 19' reach horizontally to the back part of the column where they again pass over two other sprockets 21, 21 before reaching down to the drums 4, 4'. The casing 11 is furthermore provided with a drawer type cover 22, which is only opened for charging. A metal protector 23 maintains the piston rods 13, 13 free from contamination by remnants of mortar and particles of dust, both of which might otherwiseafi'ect the perfect sliding action thereof along their guideways.

There is now described the operation of the machine. The casing 11 is first. placed in its lower position, that is, at the base 1 of the machine. The latter is then placed beside the wall to be plastered, this being rendered easy because of the casters 2, 2' which are movable and allow motion in all directions. The two leading casters 2, 2 are then mounted atop the guide-rail 24 (Fig. 2) which is a channel or U-shaped member placed horizontally along the wall to be plastered. This guiderail 24 is previously anchored to the wall at a suitable distance therefrom, so that the machine after being mounted on said guidearail, will have the ends of its leading or front rails 7, 7' spaced fromv the wall a distance equal to the required thickness of plaster. In order to render. easier the mounting of said guide-rail 24, it should extend laterally to the foot of the wall and then rise. some cm., for example, being provided at this latter part with holes for the passage therethrough of nails 25 which attach said guide-rail to the wall, as shown in Fig. 4. When. the leading casters 2, 2 are mounted on the guide-rail 24, the machine is movable only in a lateral direction and cannot advance or move backward because. of the guide-rail 24. By. means of two large screws 5, 5' the back part of the machine may then be easily raised, thus rendering the front surface of the column (or casing 11) substantially parallel to the wall (a sort of mean parallelism, of course, since the wall will exhibit recesses and projections) and at the selected distance therefrom, which last should be equal to the required thickness of plaster. In order that the rotation of the machine around an imaginary line going through the leading casters2, 2 thereof (which rest, as shown above, on the guide-rail 24) may be normally effected, the two screws 5, 5 are capable of swivelling action. Their respective nuts 32, 32' are fixed to shafts which are, in turn, journalled in bearings attached to the back part of the base 1. The column 7, 7', 8, 8' is erected at an angle of less than 90 with the base, so. that, when these two screws 5, 5' are completely screwed in, the column remains a sufficient distance away from the wall surface to permit the free lowering of the case ingll, without risk of contact of the blades 16, 17 there.- of with the wall. In short, the horizontal alignment is determind by the guide-rail 24 and the vertical align-. ment is determined by the two swi elling screws 5, 5". Once said alignment has been obtained, the column is firmly retained in the desired position by means of shore ing elements 26 and tie-rods 27 (Fig. 3). These shoring elements or struts 26 abut against the leading rails of the column and rest upon the flooring of the room, atop wedge-shaped blocks 28. The ends of the tie-rods 27 rest on the floor and on the ceiling of the room and are stressed by means of turnbuckles 29 placed at an intermediate point thereof. This type of shoring ensures, Sllbr. stantially perfect stability of the column, which is an essential requirement for the satisfactory operation of the machine, since any deflection or wobbling of the column will result in faulty plastering. Since the column has to be portable and therefore light andsomewhat 4 flimsy, the importance of this type of shoring. willbe obvious to one skilled in the art.

After the machine has been suitably shored in position, the piston 12 thereof is retracted, as well as the casing cover 22, the casing thus being made free for receiving the plaster or mortar, which last is brought in by hand from a concrete-mixer. This charging operation of the casing 11 can be effected from either side thereof. The mortar should be carried in a suitable receptacle, each receptacle having conveniently a capacity equal to half that of the casing 11 and being preferably provided with a spout for better pouring out of the mortar. The contents of two such receptacles should sufiice for completely filling the casing 11 and the two full receptacles may be easily carried by an ordinary man. After the charging operation the casing 11 is again closed. The operator then actuates a control lever 30 (Fig. 3), thus putting the motor 3 in operation. The chains 19,

19 which are connected with the drums 4, 4' in turn coupled with the motor 3, efiect movement of the piston- 12 within the casing 11, thus pushing the mortar against the wall surface. After the mortar has occupied the whole empty space formerly existing between the casing and the wall, no further progress of the piston is possible. The casing 11 will then be pulled upwards, along the column rails. empty space in front of the piston 12, allowing it to ad vance further, and so on in similar manner. In reality, the movements of the piston 12 (toward the wall) and of the casing 11 (upwards) are not alternating but simultaneous. This close interdependence between the compression of the mortar and the displacement of the supplycasing-11 is indeed one-of the most important characteristics of the machine. This provides the. desirable automatic supply of the rough and final plastering blades 16, 17 with mortar, and thereby ensures a faultless and uniform coating of plaster, with no difficulty due to the wall recesses and projections. The quantity of mortar required for the perfect operation of said blades is always changing, but the casing 11 will always react to these changes in a satisfactory manner. When the easing 11 reaches the upper part of the column 7, 8 the piston 12 will be almost at the end of its stroke, since the capacity of the casing 11 is approximately equal to the volume of plastering to be done in each operation.- When this happens, the casing itself, by means of a suitably arranged projection, actuates an electric switch placed at the upper part of the column, thereby disconnectingthe motor 3. After removal of the struts 26 and loosening of the tie-rods 27, the column may then be moved away from the wall after the unscrewing of said swivelling screws, 5, S, which are then operated till the rear casters 2', 2' of the base 1 rest again on the floor. The machine may then be moved laterally to an adjacent plastering position (allowing some overlapping of the previous plastering), whereupon the two front casters 2, 2 will ride on the guide-rail 24 and the two rear ones 2', 2 on the flooring of the room, or else on top of a thin metal plate, should the flooring be too rough for the rolling movement. The operator then actuates the control lever 30 in the opposite sense so as to lower the casing 11 to its former position at the base of the column, and the operations may then be repeated exactly as described above.

It will be seen that the casing when in its lowermost position, will be entirely full of mortar, thus having maximum weight. The situation reverses itself 'at the top of the column, where the casing 11 will'be practically empty, thus presenting minimum weight. On the other hand, the piston 12, on starting to operate, will have to move all the mortar existing in the casing 11, whereas at the top of the column this displacing movement will be appreciably less, because of the smalleramount of mortar to be pushed forward. certain compe satioll thus exists between the variations to resist- This will present another open or ance offered to the displacements of the casing 11 and of the piston 12. This compensation is however not sufficient, since, in actual practice, the resistance opposing the (upward) progress of the casing 11 diminishes more rapidly than the resistance opposing the advance of the piston 12 (against the wall). On behalf of perfect compensation the machine is provided with a very simple device. Chain 34 (Fig. 3), having a suitable total weight (approximately 65 pounds), is suspended from the center of the column. Thus casing 11, when rising, will receive link by link on its cover, the chain 31, thus automatically compensating the loss of weight due to the escape of mortar. Then again, this compensating chain 34 will prevent too great a displacement of the center of gravity of the supply casing 11, which might otherwise overload the guides thereof.

Solely by way of example and not of limitation, there is now described the construction and operation, of a machine according to this invention.

The height of the column may be feet, which is the standard head-room in most modern buildings. For greater heights, higher columns and casings of larger capacity may be used, or else the same machine may be used positioned atop rows of scaffolding 10 feet high. The standard casing may have a capacity for coating with plaster, in one operation, an area of approximately 3 feet x 2 /2 feet and inch thick or, in other words an area of 7 /2 square feet with an average thickness of $5 inch. Such an operation will probably require no more than 4 minutes, which represents 1 the time required by a skilled mason, besides ensuring less loss of material and work nearer perfection.

The machine herein described can apply plaster almost from the floor level to about 10 inches from the ceiling, and these remaining portions may be easily plastered conventionally, by hand.

The machine may be made of steel and aluminum, for example, in order to provide great ruggedness and small size.

I claim:

1. A machine for plastering walls comprising a base having a forward and a rearward portion, a column mounted upon the forward portion of said base, guide rails in the forward portion of said column, a casing for containing plaster vertically movable on said rails, said casing having an open front end to be positioned adjacent a wall, a piston forwardly movable in said casing, adapted for applying a layer of plaster to said wall, means for moving said piston forwardly, and means raising said casing on said rails, said last-named means operable upon 6 the encountering of substantial resistance to the forward movement of said piston, said means for moving said piston forwardly and said means for raising said casing comprising piston rods aflixed to the rear of said piston, a sprocket mounted on each side of said casing forwardly of the rear ends of said rods, a pair of sprockets mounted in the upper end of said column each in vertical alignment with one of said first-mentioned sprockets, drums mounted on the rear portion of said base, and a pair of chains each attached at one end to the rear portion of one of said rods, each entrained over associated sprockets carried by said casing and said column and each having its other end connected to said drums, and means for rotating said drums.

2. A machine as defined in claim 1 wherein said casing has aflixed thereto an upper and a lower blade, said upper blade positioned at the height of said opening and having three flexible sections provided with lower projecting edges, and said lower blade being attached to the casing at the lower end of said opening and including a single rigid section, said blades having their lower edges in vertical alignment.

3. A machine as defined in claim 2 including an aligning device for the adjustment of the front face of the column to the surface to be plastered, said aligning de vice including a pair of swivelling screws disposed in the rear portion of said base, respective nuts for said screws, bearings mounted on the base, a pair of shafts journaled therein and attached to said nuts, forward and rearward casters for said base, and a separate guide rail over which ride the forward casters of said machine during lateral movement thereof along the wall.

4. A machine as defined in claim 1 wherein means is provided for maintaining substantially constant resistance to the upward movement of said casing, said means comprising a chain suspended from the upper end of said column substantially centrally above said casing whereby the lower end portion thereof will accumulate upon and add weight to said casing upon said upward movement.

References Cited in the file of this patent UNITED STATES PATENTS 10,590 Hussey Mar. 7, 1854 378,453 Miles Feb. 28, 1888 1,652,089 Caley et a1. Dec. 6, 1927 2,630,703 Sommers Mar. 10, 1953 2,711,098 Ames June 21, 1955 

